Tokina 16-50mm f2.8 DX is an Auto Focus (AF) Standard Zoom lens with APS-C / DX max sensor coverage. When mounted on a APS-C / DX sensor camera, it will give you an FF equivalent focal range of 24 - 75mm. With a max aperture of f2.8, this lens is fast on wide end and equally fast at 50mm with a max aperture of f2.8. Tokina 16-50mm f2.8 DX is weather sealed which makes it an ideal lens for outdoor use, especially when coupled with a weather sealed camera body.